System for recovery of valuable constituents from normally wasted materials



2,978,063 TUENTS April 4, 1961 TERIALS SYSTEM FOR RECOVERY FROM NORMAL Filed April 6, 1959 INVENTOR. W. W. FORD A. M. L. KUBE HMLW M @L 9 R om mm I MMIHHI mm 3 m m vm mm 5 A TTO/PNEVS Unit tars g I V [2,978,063 i SYSTEM FOR RECOVERY, F 'vALUABLE CON; I s uTUENrs FROM .NORMALLY wasran.

WiIIiamWJ'Ford and Adolph M. Liaise, Phillips, i Y r assignors to Phillips. Petroleum Company, a corporalieu of Delaware .Filed Apnsgrsss; summar es 5 Claims. "(CL 1831-2) invention relates to a system for the recovery of valuable constituents in gases normally sent to the I 1 Patented Apr. 4, 1961 I i i Z gramof summin constructed in accordance withthe invention.

a Refe 'ngnow totheidrawing, gases enter the. flareline j1 0 from a gathering system (not shown), via conduit 11 and pass through an induction line. 12 to beneath the surface of the liquid 13 in" tank' 14so as to produee a pressure. of '2 or 3 poundsin flare line 10.

' Gases. which escape through the liquid trap in tank'14 pass through line ls to the flare. via conduit'ltiai Liq trap. 16 is positioned in flare line 10 and is connected in par allelwith the liquid trap of tank 14 and contains liquid 17. The liquid head in trap 16 will normally be maintained at a level to produce a-pressure 2 or 3 pounds higher than that produced by the liquid head in tank 14. A scrubber 7' can be placed in conduit 10 downstream from liquid trap 16 to recover liquid blown from trap 16 by a surge of high pressure in flare conduit 10. The liquid is;returned to trap 16 via conduit 8 containing'check valve 9if scrubber '7 is. elevated sufliciently for gravity flowr Check valve 9 can be replaced by a pump (not shown) if scrubber 7 is notele'vated sufliciently for grav;

to the flare line under normal operating lj'conditions.

The. gases in a flare line system .usuallyfrepreseut 'a' heterogeneous mixture or gases as a result or their having briginated from a variety of sources and it is notjalways desirable to introduce such mixture to; a lo'w'pressure point in the system. Furthermore, a liquidtraphasj not always proven' successful becauseia water trap has'a tendency to freeze during unexpected cold weather and an oil traphc's' atendency to accumulate condensable ,hydroca'r bo'n materials within itself and tofpass lugsof liquidto the flare as a resultflofsuch increase in "volume through condensation of liquefied material. f i

a, In accordance with this invention, provision is made for the absorption of condensable materials, fromfthe gases being passed to the flare line, for further processing and rusefand for' passing the noncondensable gases to the fuel line to be usedfor supplying heat to the plant under consideration. Further, inaccordance with this invention, provision is-made for 'a water" trap in the line to the flare to prevent venting of gases during normal operation and. a .by-pass. line to carry mater ials going to the flare through an oil trap maintained at a slightly higher pressure than that of the water trap so that a substantially uninterrupted flow to the flare 'is assured at alltimeswhen a. flow 20f largevolume tothe :flareis required. I

it is an object of this inventionto provide a system for"separating the condensable. materials Pre sman"; flare line from the ;noncondeusable materialsgsending the noncondensable materials to be used as iuel and processing the condensable materials for further use. 'It isv also an object of this invention to provide two dissimilar liquid traps in the flare line connected. inparallel so that substantially uninterrupted flow to the flare F ffl .Abranch line 18 conducts gas from flare line 10 to a first liquid-gas separator 19,- where any liquid which is present in the. gas accumulates in vessel 19 and is re;

moved by means of conduit20 through motor valve 21, which is actuated by liquidlevel control 22; Gases removed .from vessel 19, via conduti 23 are compressed'iby compressor 24, cooled by cooler 25 and passed into] a second liquid-gas separator 26. Liquid is removed from vessel 26 via conduit 27 through motor valve 28 which is controlled by liquid levelcontrol 29., Gas from vessel 26 passes through conduits 30, "31 to absorber 32 where it isjcontacte'd with afliquid absorbent introduced via conduit 33; The richfab'sorb'ent passes from ab} sorber '32 through conduit34 to stripper 35 fromwhenci desorbed materials are removed via conduit '36, cooled in cooler 37 and removed. via conduit 38. The'lean'soh vent or absorbent is removedfrom stripper 35 viaeon duit 39, is cooled in cooler 40 and returned to absorber 32 via conduit 33. Heat is added to stripping vessel 35 by means of a heater41, which can be any conventional heating means such as steam, electricity and the like.

' A recording flow controller 42 operatively connected to conduit 31 actuates a normallyopen motor valve43 so as to limit the flow to absorber 32 to a predetermined maximum value.

A pressure controller 44 operatively connected to conduit 23 actuates a normally closed motor valve 45 so as to open said valve whena pressure in conduit 23 1 falls below a predetermined value so as to recycle com pressed gas back: to the compressor inlet at times when the pressure in the flare line system is abnormally low. The condensed materials recovered from vessels 19, 26 and 35 arelremoved via a common conduit 46.xNoi1 condensed gases are passed to and supply systemvia is accomplished under allconditions of operation. It is still another object of this invention to' provide a compression system and an absorption system for'treating mum. pressure. on. the..compression, system is i, controlled the materails inthe. flare .linesystem wherein; the 'miniand the maximum flow. rate to the. absorption; system is controlled. Other and further objects and advantages conduit 47. 7

Positive control of compressor suction pressure can be obtained by supplying make-up fuel gas from, an outside source via conduit 48.. If fuel gas is supplied via conduit '48, pressure controller-44 will actuate normally closed motor valve 49 instead of, or in addition to; motor valve ,45 v (The water" level in vessel 14 can" be maintained-by {conventional means such as aiwaterinlet valveoperated by -a liquid level control means." Heating means can be supplied to heat the water in vessel 14 during cold weather if such is desired.

The head of water in vessel 14 is selected so that a back pressure of from about 1 to about 3 pounds per square inch gauge is maintained in the flare system 10 and about" 1' to 2 pounds-higherthanthat of the-liquid-trap-- of vessel 14. The gas in the conduit 31 is compressed to some. preselected value such as about 68 p.s.i.g. and the recording flow controller -42'is-' set'at apreselectedf' valuefor example about 3 mm. standard cubic feetpcnday: The pressure controller'44 is'set to'open' valve 45 at some predetermined'minimum'pressure inconduit 23 for example about /2 p.s.i.g. j

' From the above, it eanlbe seen that all' of the non condensable gases which enter the. flare line system are used for fuel under normal operation andfthat the condensable materials are recovered for further processing. When gases pass into the flare. line system at an; abnormally high rate, the excess over that whichfl'can' be used as fuel is passed to the flare. By the practice of thisrinvention, the flare line is always capable of passing large quantities of gasat relatively low pressure and; at the same time reverse flow of gas through the flareline is substantially completely prevented.

If desired, the pressure controller 44 can be opera: tively connected to a means for shutting down. the compressor 24 if the pressure in conduit 23. falls tora predew termined low value which might result in harm to the compressor. caused to actuate a switch which opensthe operating electrical circuit to the motor operating compressor 24 Thus, the pressure controller 44 can be.

if an electric motor is used, or can be caused to close a valve in a steam line if steam power is used to operate the compressor.

Reasonable variations and modifications are possible within thev scope of the present disclosure without'departing from the spirit and scope of the invention.

That which is claimed is:

l. A. system for recovery of valuable constituents from gases sent to a flare which comprises, in combination, a flare conduit connected to a flareand'to a source ofgases; a first liquid seal containing water as the sealing liquid operatively connected to said flare conduit was to pass 'gas to said flare when a predetermined first pressure is attained in said flare conduit; a second liquid seal containing oil as the sealing liquid operatively connected to said flare conduit so as to pass additional gas to said flare when a predetermined higher second pressure is attained in said flareconduit; means to collect. oil blown from said second seal andto return same to said second seal; a first gas-liquid, separator; conduit means connecting said first separator to said flare conduit at apoint upstream from said first liquid seal; a second gas-liquid separator; means to remove gas from said first separator, to compress and cool said gas. and pass sameto said second separator; means to remove liquid from said separators; absorber means containing an absorbent to absorb selected components from a gas; means to pass gas: from said second separator. to said absorber when the pressure in, said; flare conduit is above a predetermined value; means to passgas; from said second separator to said first separatorwhen thegas pressure in said flare COD? duitzis, below. said predetermined value; stripper means to remove absorbed components from said absorbent; means to pass absorbent containing said components from said absorber to said; stripper; means to remove gas,

seals connected to said flare conduit in parallel so as to pass-anincreasing'volume of hydrocarbons to said flare at increasing increments of pressure in said flare conduit; separator means for separating liquids and readily condensable gases from hydrocarbons; means for passing hydrocarbons to said=separator means from said flare conduit at a point upstream from said seals; means for; removing liquid from said separator means; absorber means forremoving valuable constituents from. a gas; means for passing gas from said separator means to said absor'berf means; means for recoveringgas from saidabsorber means; and means' for recovering valuable constituents from said absorber means.

3. A system for recovering fuel gas and condensable hydrocarbons from normally wasted hydrocarbons sent to a flare which: comprises, in combination, a flare; a flare conduit; liquid seals operatively connected to said flare conduit in parallel so as to maintain a predetermined minimumpr'essure in said flare conduit'and'to, pass increasingamounts ofhydrocarbons to said flare at increasingvincrements of pressure in said flare conduit; means for removing hydrocarbons from said flare conduit at a point, upstream from said seals; means for recovering liquidfrom the, removed hydrocarbons; means for condensing and. recoveringcondensable hydrocarbons from remaining'removed hydrocarbons; and means for recoveringremainingfuel gas from said condensing means.

4. A system for recovery of condensable constituents from hydrocarbons sent to a flare which comprises, in combination, a flare; a flare conduit; a plurality of'liquid sealsl connected to said flare conduit in parallel so as to pass an increasing volume of hydrocarbon gases to Y I said flare, at increments of pressure in said flare confreed ofrsaid components from said, absorber; means to duit; a first gas-liquid separator; conduit means connecting said'first separator, to said flare conduit at a point upstream from said liquid seals; a second gas-liquid separator; means to remove gas from said first separator, to compress and cool said gasand pass same to said'second separator; means to recover liquid from said separators as said condensable constituents; means to pass gas from second separator to said first separator when thepressure in said flare conduit is below a predetermined minimum; and means to pass gas from said second separator to a fuel gas supply means when the pressure in said flare conduit is above said predetermined minimum.

5'. A system for recovery of condensable constituents from hydrocarbons sent to a flare which comprises, in combination, a' flare; a flare conduit; a plurality of liquid seals connected to said flare conduit in parallel so as to pass :an increasing volume" of hydrocarbon gases to said flare at' increments of pressure in said flare conduit; a first gas-liquid separator; conduit means connectingsaid first separator to said" flare conduit at a point upstream from said liquid seals; a second gas-liquid separator; means to remove gas from said first separator; to' compress andcool said gas and'pass same to said second separatorymeans torecover' liquid from saidseparators-as said condensable' constitutents; means to supply gas to said first separator, when-the pressurein said flare conduit is below-a predeterminedminimum; and means-to pass gas fronrsaid second separatorto a fuel gas supply means whenzthepressure insaid flare conduit isabove said predetermined minimum.

References Cited in the file of this patent UNITED STATES PATENTS 2.734562 Haberle; Feb. 14; 1956 2,792;010 Strunk May 14, 1957 Carter Aug; 11, 19.59 

